Didn’t reciprocate hand wave of passing car. How can I recover?

Out in the sticks with single lane bitumen and red dirt on either side forcing cars half onto red dirt when passing.

Car comes up ahead, but the side of the road is a bit pitted out, so I focus on the road as I’m passing.

After passing, my wife says the words that have haunted me since it happened: “you didn’t wave back?”

I unknowingly did the most un-Australian thing imaginable and prioritised personal safety over social courtesy. Devastating…

Has this happened to anyone else? How did you recover